Roller bit



Dec. 7, 1943. J. c. FORTUNE 2,335,929

ROLLER BIT Filed July 13, 1942 Jnea C 1 572202- Patented Dec. 7, 1943ROLLER w James O. Fortune, Houston, Tex assignor to Reed Roller BitCompany, Houston, Tex, a corpora- Y tion of Texas I Application July 13,1942, Serial No. 450,668

6 Claims.

This invention relates to well drilling apparatus and more especially isdirected to roller drill bits. In prior art roller bit constructionsdifllculty has been encountered in obtaining adequate strength in thesmaller sizes because the limited dimensions of the device restrict thesizes and load-capacities of the supports, shafts, bearings and cutters.

Bits having a single roller cutter have been developed and various meanshave been provided for feeding drilling fluid from the drill stemthrough the drill bit and into the well bore, but all of theseimprovements have failed to attain the effectiveness desired.

In many instances the manner of feeding the drilling fluid into the wellbore tends to erode the bottom of the hole especially in soft formationand causes the bit to deviate laterally resulting in a crooked bore.

An object of this invention is to provide a roller bit constructionwhich will avoid the prior art disadvantages.

Another object of this invention is to provide a roller bit having asingle cutter and constructed to feed drilling fluid directly to thecutter and into the hole drilled in a novel manner.

A further object of this invention is to provide a drill bit havingpassages for supplying drilling fluid to the cutting element thereof andinto the bore of the hole drilled which avoids erosion of the bottom ofthe bore and any tendency for lateral deviation of the bit.

With these and other objects'in view which will appear more fullyhereinafter, the invention resides in the parts and combinationsdescribed in the following specification and illustrated in the drawing.

In the drawing:

Fig. 1 is an elevational view of a drill bit constructed to embody thefeatures of the present invention.

Fig. 2 is a longitudinal sectional view of the bit shown in Fig. 1illustrating the same in a well bore.

Fig. 3 is a botom view of the drill bit illustrated in the precedingfigures.

It has been found that a roller drill bit constructed with a singleroller cutter can be con-' structed for use in drilling wells ofcomparatively small bore and still employ a relatively large cutter,shaft and bearing which will impart great strength and durability to thestructure.

The present invention utilizes such type of construction. As shown inthe drawing the drill bit comprises a hollow body I having two legs 55 2and 3 depending therefrom. Leg 2 is of light solid construction and isof a shorter length than the leg 3. 0n the other hand leg 3 is rathermassive and extends downwardly beyond leg 2. In addition leg 3 has itslower end portion projecting radially inwardly to the axis of rotationof the bit body and is provided with an aperture 4 to receive the lowerend of the inclined roller cutter shaft 5,. The other end of shaft 5 maybe integral with the lower end of leg 2.

At this point it should be noted that the cutter body is formed of twoor more portions, one portion carrying the leg 2, and another portioncar-- ry'ing the leg 3, the portions being welded or otherwise joinedtogether along the line 6. Such 'a construction enables the bit to bemore easily and economically made and assembled. In assembling theportions together the roller cutter I may be mounted-0n the shaft 5 andthe lower end of said shaft may be inserted in the opening 4 and weldedtherein when the portions of the bit body are joined together.

With the roller cutter shaft 5 supported as illustrated, a substantiallyconical roller cutter I may be rotatably mounted thereon with its largeend adjacent the leg 2 and its small end adjacent the lower end of theleg 3. A roller cutter so mounted will effectively cut into theformation at the bottom of the well bore without undue wear on the teethof the cutter.

In order that the drill bit as a whole may be caused to rotate about itstrue axis and not gyrate within the well hole, two reamer cutters 8 and9 are provided. These reamer cutters are mounted for rotation onsubstantially vertical axes disposed on each side of leg 3.

As a matter of fact, the reamer cutters 8 and 9 are supported forrotation by upper and lower lateral extensions Ill and H on each side ofthe leg 3. With this construction the two reamer cutters 8 and 9 and thecutter 1 are arranged in a substantially triangular formation so thatthere will be a three-point bearing contact between the reamer cuttersand the cutter I and the wall of the well bore. It will be found that byspacing the reamers andv cutter approximately apart the cutter will beproperly positioned in cutting relation to the bottom of the well bore.

The inner portion of the hollow bit :body I is provided with a taperedthreaded part I! adapted to receive the lower end of the drill stem.

Careful consideration has been given the routing of drilling fluidthrough the bit of the pres cut invention and in this connection it willbe noted that leg 3 has a passageway l3 formed therein whichcommunicates-with the chamber H provided in the bore of the bit body.Passageway I 3 extends downwardly and outwardly through the leg 3 andcommunicates with a slotlike recess l5 formed in the outer surface ofthe leg 3 and extending substantially in an axial direction. Closing theouter portion of the slot i5 is a deflection shield i8 which' is weldedto the leg 3 and extends downwardly toward the bottom thereof. It willbe noted that the lower end of the slot I5 is left open to provide adischarge oriflce I! for the drilling fluid which is supplied throughthe drill stem into the chamber l4 and from which it is passed throughthe passageway l3 downwardly into the duct formed by the slot l5 havingits lateral opening closed by the shield l6. It will be noted that thebottom of the slot I 5 is deflected inwardly at its lower portion asindicated by reference character l8 and that the lower end of the shieldI6 is bent inwardly as indicated by reference character l9. This willtend to direct the drilling fluid discharged i'rom the orifice l1radially inwardly toward the roller cutter By bending the lower end ofthe shield IS in the proper direction the stream of drilling fluid maybe deflected to either precede or follow the roller cutter I in itspassage around the bottom of the hole which is being drilled, or may beaimed directly at the cutter I.

In addition to the flow of drilling fluid through i the leg .3 and downinto the well hole, the present invention also provides for the playingof a stream of drilling fluid onto the teeth of the cutter I in order toclean the same. For this purpose the lower end of the chamber i4 isprovided with a discharge opening 20 into which is fitted a nozzle 2i.

The size of the orifice 20 and the nozzle 2| is such as to cause astream of relatively high velocity'to be discharged onto the teeth ofthe cutter when out of engagement with the formation into which the wellis being drilled.

It will be noted from the drawing that the cross section of thepassageway I3 is much larger than that of the oriflce 20 and thisprovides for the major portion of the drilling fluid flowing through thepassageway 13 and out through the duct formed by the slot IS. Thedischargeof the major portion of the fluid through the orifice I! at thelower end of slot l5 confines the circulation between the end of thedrill bit'and the bottom of the well hole and deflects the return flowaround the cutter I and along the reamer cutters 8 and 9.

Oneof the principal features of the drilling fluid flow in the presentinvention is that the large fluid opening formed by the orifice I! atthe lower end of the slot l5 permits a large volume of flow of drillingfluid to pass through sa d orifice at a comparatively low velocity intothe bottom of the well hole. It is more desirable to have a large volumeof flow carrying away the formation as fast as it is out rather than tohave asaaosa fluid is supplied so as to effectively wash away thecutters without any 1 formation cut by the roller letting action on thebottom of the hole. Having described my invention, I claim: 1. A rotaryroller drill bit comprising a hollow body having 'two legs dependingtherefrom, one

of said legs having a passageway therein inclined downwardly from theinterior of the ho1- low body toward the outer portion of said leg, a

rotary cutter supported for rotation between the ends of said legs, saidleg having the passageway therein also having a recess formed in theouter surface thereof, communicating with the passageway and extendingaxially of said leg, and a shield welded to said recessed leg andclosing the \outer portion of said recess to convert said recess into aduct for the discharge of drilling fluid fed down through the hollowbody and passageway.

2. A rotary roller drill bit comprising a hollow body having two legsdepending therefrom, one of said legs having a passageway thereininclined downwardly from the interior of the hollow body toward theouter portion of' said leg, a rotary cutter supported for rotationbetween the ends'of said legs, said leg having the passageway thereinalso having a recess formed in the outer a small volume high velocityflow which will have preciated that the present invention provides adrill bit in which the roller cutters are disposed in the most usefulmanner and in which drilling surface thereof, communicating with thepassageway and extending axially of said leg, a shield welded to saidrecessed leg and closing the outer portion of said recess to convertsaid recess into a duct for the discharge ,of drilling fluid fed downthrough the hollow body and passageway, and.

a nozzle communicating with the hollow body and positioned above thecutter for discharging a Jet of drilling fluid onto said cutter.

3. A rotary roller drill bit comprising a hollow body having two legsdepending therefrom, one

of said legs having a passageway therein inclined downwardly from theinterior of the hollow body cutter supported for rotation between theends of said vlegs, said leg having the passageway therein also having arecess formed in the outer surface thereof, communicating with thepassageway and extending axially of said leg, and a inwardly of the legcontaining the same and the lower end of said shield being curvedinwardlyfluid from the duct to direct the discharge of toward saidcutter. V

4. A rotary roller drill bit comprising a hollow body having two legsdepending therefrom, one of said legs having a passageway thereininclined downwardly from the interior of the hollow body toward theouter portion of said leg, a rotary cutter supported for rotation saidlegs, said leg having the passageway therein also having a recess formedin the outer surface toward the outer portion of saidleg, a rotarybetween the ends of thereof, communicating with the passageway and 1extending axially of said leg, a shield welded to said recessed leg andclosing the outer portion of said recess to convert said recess into aduct for the discharge of drilling fluid fed down through the hollowbody and passageway, the

lower inner wall of said recess being curved inwardly of the legcontaining the same and the lower end of said shield being curvedinwardly to direct the discharge of fluid from the duct toward saidcutter, and a nozzle communicating with the hollow body and positionedabove the cutter for discharging a jet of drilling fluid onto saidcutter.

5. A rotary roller drill bit comprising a hollow body having two legsdepending therefrom, one of said legs having a passageway thereininclined downwardly from the interior of the hollow body toward theouter portion of said leg, a rotary cutter supported for rotationbetween the ends of said legs, said leg having the passageway thereinalso having a recess formed in the outer surface thereof, communicatingwith the passageway and extending axially of said leg, a shield weldedto said recessed leg and closing the outer portion of said recess toconvert said recess into a duct for the discharge of drilling fluid feddown through the hollow body and passageway, and a nozzle communicatingwith the hollow body and positioned above the cutter for discharging ajet of drilling fluid onto said cutter. the cross section of thepassageway and duct being considerably greater than that of the nozzlewhereby the greater portion of the drilling fluid will be dischargedthrough the duct.

6. A rotary roller drill bit comprising a hollow body having two legsdepending therefrom, one

of said legs having a passageway therein inclined downwardly from theinterior of the hollow body toward the outer portion of said leg, arotary cutter supported for rotation between the ends of said legs, saidleg having the passageway therein also having a recess formed in theouter surface thereof, communicating with the passageway and extendingaxially of said leg, a shield welded to said recessed leg and closingthe outer portion of said recess to convert said recess into a duct forthe discharge of drilling fluid fed down through the hollow body andpassageway, and a nozzle communicating with the hollow body andpositioned above the cutter for discharging a jet of drilling fluid ontosaid cutter, the cross section of the passageway and duct beingconsiderably greater than that of the nozzle whereby the greater portionof the drilling fluid will be discharged through the duct, and thedischarge oriflce of said duct being large enough to avoid jet action offluid discharged therefrom against the bottom of the bore in which thedrill is used.

JAMES C. FORTUNE.

